Yes you can find beginners kit for 1000 EURO, but after few years you are not beginner any more and than you need two boards five sails, three masts, three booms, fins….
Of course you need also a big car to transport the gear and job where you can take a leave when wind blows. If you travel with airplane you pay extra for cargo, than you have to rent a car or you rent a windsurf for 600 EURO / week (Fuerteventura). Not to mention your wife and kids.
Because of this and many other reasons WS was in decline before kite boom. Kite is cheaper and easier for transport, but it has some other drawbacks, so it is no replacement for WS.